(1) Background of the Invention
The present invention relates to input/output (electric) power control apparatus and method for a secondary battery and, particularly, relates to a control technology for the secondary battery during a failure in a current sensor or a voltage sensor.
(2) Description of Related Art
A Japanese Patent Application (First) Publication No. 2000-357541 published on Dec. 26, 2000 exemplifies a previously proposed input/output power control apparatus for a secondary battery. In such a previously proposed input/output control apparatus as described in the above-identified Japanese Patent Application Publication, a current sensor configured to detect an input and/or output current and a voltage sensor configured to detect a terminal voltage of the secondary battery are equipped. In addition, a residual capacity (viz., a charge rate or SOC: State Of Charge) of the secondary battery is detected in accordance with the detected input and/or output current and the terminal voltage and a control over input and output powers (or simply called input/output powers, the input power means a charging power and the output power means a discharging power) on the basis of the detected residual capacity. Hence, when either the current sensor or the voltage sensor has failed, it becomes difficult to perform a normal (or an ordinary) control over the input/output powers of the secondary battery.
In the previously proposed input/output power control apparatus disclosed in the above-described Japanese Patent Application Publication, in a case where the voltage sensor is detected to fail, a method is described in which the input and/or output current is reduced to a value smaller than an ordinary input and/or output current (or an ordinary input and/or output electric power) or limited to a value equal to or smaller than a predetermined value. Thus, while individual battery cells are (or the secondary battery is) protected, the input/output powers thereof are controlled.